Am 16.11.2012 10:35, schrieb Paolo Bonzini:
Il 15/11/2012 23:18, Stefan Weil ha scritto:
Am 15.11.2012 21:52, schrieb Paolo Bonzini:
Il 15/11/2012 19:01, Stefan Weil ha scritto:
Hi Paolo,
this patch breaks QEMU on 32 and 64 bit hosts, native and with Wine.
It's easy to reproduce the SIGSEGV crash: just add a -snapshot option.
Obviously the critical code is executed only when this option was used.
I cannot reproduce this, so it must be an assembler or linker bug.
Can you try the alternative code that is used for Mac OS X?
The code which is used for Mac OS X also compiles and
results in the same run-time bug with Wine:
Ok, I reproduced the original binutils bug, and found a typo in the
weakrefs implementation. Does this work for you?
diff --git a/compiler.h b/compiler.h
index 55d7d74..d552757 100644
--- a/compiler.h
+++ b/compiler.h
@@ -50,11 +50,12 @@
# define __printf__ __gnu_printf__
# endif
# endif
-# if defined(__APPLE__)
+# if defined(__APPLE__) || defined(_WIN32)
# define QEMU_WEAK_ALIAS(newname, oldname) \
- static typeof(oldname) weak_##newname __attribute__((unused,
weakref(#oldname)))
+ static typeof(oldname) weak_##newname __attribute__((unused,
weakref(#newname)))
# define QEMU_WEAK_REF(newname, oldname) (weak_##newname ? weak_##newname :
oldname)
# else
+#error
# define QEMU_WEAK_ALIAS(newname, oldname) \
typeof(oldname) newname __attribute__((weak, alias (#oldname)))
# define QEMU_WEAK_REF(newname, oldname) newname
If it still doesn't work, let's make sure that this reduced testcase works
for you:
Tested-by: Stefan Weil <s...@weilnetz.de>
Great, the above patch fixes w32/w64 (native and with Wine).
Is this modification needed / does it work with MacOS X, too?
With the reduced testcase, I get the same results as in your test.
Regards
Stefan
g1.c:
#include<stdio.h>
int f() { printf("strong"); return 82; }
int g() { printf("strong"); return 83; }
g2.c:
#include<stdio.h>
static int weak_f() { return 42; }
static int weak_g() { return 43; }
typeof(weak_f) f __attribute__((__weak__, __alias__("weak_f")));
typeof(weak_g) g __attribute__((__weak__, __alias__("weak_g")));
int main() { printf("%d/%d\n", f(), g()); }
g3.c:
#include<stdio.h>
static int default_f() { return 42; }
static int default_g() { return 43; }
static typeof(default_f) weak_f __attribute__((__weakref__("f")));
static typeof(default_g) weak_g __attribute__((__weakref__("g")));
int main() { printf("%d/%d\n", (weak_f?:default_f)(), (weak_g?:default_g)()); }
Output should be:
- 42/43 for "gcc g2.c"
- 42/43 for "gcc g3.c"
- strongstrong82/83 for "gcc g1.c g2.c"
- strongstrong82/83 for "gcc g1.c g3.c"
Output on Windows is:
- 42/42 for "gcc g2.c"
- 42/43 for "gcc g3.c"
- segfault for "gcc g1.c g2.c"
- strongstrong82/83 for "gcc g1.c g3.c"
So, indeed "normal" weak symbols are broken, but weakrefs seem to work.
If the above patch doesn't work, and/or the reduced testcase fails,
please send to me:
- the .exe for "gcc g1.c g3.c"
- the .s file for g3.s
- the .o file for osdep.o
- the linked .exe (I assume both the windows and console versions fail)
- perhaps the .s file for osdep too; add --save-temps to the compiler command
line to get it
Paolo
